1. Field of the Invention
The present invention relates to a sheet member transport apparatus for transporting a sheet member with the skew of the sheet member being compensated by making the sheet member hit a registration mechanism and form a loop, and relates to an image forming apparatus using the sheet member transport apparatus.
2. Description of the Related Art
In a sheet member transport apparatus which has hitherto been used in an electrophotographic copying machine or the like, in the case of, for example, cassette paper, sheet members loaded in a paper supply cassette are supplied one by one, and fed into an image forming unit while being timed by a register roller.
For a sheet member to be fed into the image forming unit with the sheet member being accurately registered, the top edge of the sheet member is made to hit a register roller at rest, and fed excessively, and thus a loop is formed within a sheet member transport passage. After the sheet member is sufficiently registered and compensated, the register roller starts to rotate. The above construction is common.
Since the loop is set to be large in order to absorb variations of the operating time of a clutch for controlling the rotation of the roller for pushing in the sheet member, the sheet member buckles to a complex shape, and forms a loop within the sheet member transport passage.
However, in the above-described prior art, since the sheet member transport speed is usually set at the same speed as the image forming speed, the sheet member hits the register roller and buckles, and when a loop is formed, the generation of an impact sound of a pop is conspicuous. For creating a pleasant office environment, there has been demands for office machines to be less noisy. If the transport speed of the sheet member is set to be slow, the impact sound can be reduced; however, the throughput (the number of sheets printed per unit time) of the sheet member is decreased.
In Blueangel in Germany, the noise standards measurement mode is changed from the FAST mode to the IMPULSE mode, and the weight of restriction has shifted from normal sound to impact sound. Therefore, making the impact sound less noisy has become a particularly important technological problem.